Study On The Influence Of Layer Damage In R Angle Region On The Mechanical Properties Of CFRP Members

Carbon fiber reinforced composites?CFRP?are widely used in automobile body parts due to their excellent properties such as high strength,durability and good design.However,considering the requirement of assembly and connection of automotive parts,composite components with R-angle region have been widely used.Composite materials with R-angle region are often cured and deformed due to many factors in the process of forming,which affects the dimensional accuracy of the structure.In the process of connecting and assembling,secondary damage of layers will be caused due to assembly stress.Layered damage and dimensional accuracy of components will lead to damage of automotive components in the service stage,seriously affecting the reliability of composite components in the service process,reducing the service life of components,and there are potential hazards.In view of the above problems,this paper studies the delamination damage propagation law of composite components with R-angle region,and analyses the influence of delamination damage defects and geometric factors of component size on the mechanical properties and delamination damage propagation behavior of structural components in the process of forming and assembling.The main research work of this paper is to study the effect of delamination damage propagation law of composite components with R-angle region on the mechanical properties and delamination damage propagation behavior of structural components.As follows:?1?Combining progressive damage mechanics model with cohesion model,using three-dimensional Hashin failure criterion and continuous stiffness degradation criterion of materials,according to the model data in the literature,the progressive damage model of C-rib with R-angle region is established.The calculated results are basically in agreement with the experimental results in the literature,which verifies the validity of the model.?2?Combining with practical application,the C-rib assembly model with R-angle region is established.The mesh-independent discussion of the model is carried out,and the mesh is divided reasonably to achieve accurate calculation of the model.The effects of delamination defect parameters on structural mechanical properties and delamination damage propagation behavior are analyzed.The results show that the larger the size of delamination defect is,the lower the mechanical properties and the faster the delamination damage propagation is;the closer the thickness distribution of delamination defect is to the middle layer,the lower the mechanical properties of the structure and the more obvious the delamination damage propagation is;the location of delamination defect has little effect on the mechanical properties of the structure The bearing capacity of the structure under compressive load is the strongest,the delamination damage expands faster,and the stiffness of the structure under shear load is the lowest.?3?Analyzing the influence of geometric factors on the strength,stiffness and delamination damage extension of composite members in R-angle region,it is found that when R-angle is obtuse,the mechanical properties of the structure are larger than that of R-angle is acute,but R-angle deviation will affect the delamination damage extension of the structure.When R-angle deviation exists,the delamination damage extension is more serious,and the radius of R-angle increases.With the decrease of mechanical properties,the delamination damage extends more severely,and with the increase of plate thickness,the bearing capacity and stiffness of the structure increase,and the expansion area is smaller.When the laying mode of composite components is the[90/45/135/0]_2s,the mechanical properties of the structure are poor and the delamination damage extends seriously.This kind of laying mode should be avoided in the forming process.